Annotator (#1861)

<!-- This is an auto-generated description by cubic. -->
## Summary by cubic
Adds an in-app screenshot annotator to the Preview panel for Pro users
so you can capture the current app view, draw or add text, and submit an
annotated image to chat.

- **New Features**
- Pen button in PreviewIframe to toggle annotator; captures a screenshot
via worker messaging and displays it in a Konva canvas.
- Tools: select, freehand draw, and draggable text; supports undo/redo,
delete, and resizing with Transformer. Canvas scales to the container.
Includes a color picker.
- Submit exports a PNG and attaches it to the chat via useAttachments;
prefills the chat input; annotator auto-closes after submit.
  - Pro-only: non-Pro users see an upsell screen.
- State atoms added: annotatorModeAtom, screenshotDataUrlAtom,
attachmentsAtom; PreviewIframe now handles dyad-screenshot-response
messages.

- **Dependencies**
  - Added konva, react-konva, perfect-freehand, and html-to-image.
- Proxy now injects html-to-image and the new dyad-screenshot-client.js
for screenshot capture.

<sup>Written for commit 580aca271c5993a0dc7426e36e34393e073bd67b.
Summary will update automatically on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

e2e-tests/annotator.spec.ts

@@ -0,0 +1,75 @@
+import { testSkipIfWindows } from "./helpers/test_helper";
+import { expect } from "@playwright/test";
+import fs from "fs";
+
+testSkipIfWindows(
+  "annotator - capture and submit screenshot",
+  async ({ po }) => {
+    await po.setUpDyadPro({ autoApprove: true });
+
+    // Create a basic app
+    await po.sendPrompt("basic");
+
+    // Click the annotator button to activate annotator mode
+    await po.clickPreviewAnnotatorButton();
+
+    // Wait for annotator mode to be active
+    await po.waitForAnnotatorMode();
+
+    // Submit the screenshot to chat
+    await po.clickAnnotatorSubmit();
+
+    await expect(po.getChatInput()).toContainText(
+      "Please update the UI based on these screenshots",
+    );
+
+    // Verify the screenshot was attached to chat context
+    await po.sendPrompt("[dump]");
+
+    // Wait for the LLM response containing the dump path to appear in the UI
+    // before attempting to extract it from the messages list
+    await po.page.waitForSelector("text=/\\[\\[dyad-dump-path=.*\\]\\]/");
+
+    // Get the dump file path from the messages list
+    const messagesListText = await po.page
+      .getByTestId("messages-list")
+      .textContent();
+    const dumpPathMatch = messagesListText?.match(
+      /\[\[dyad-dump-path=([^\]]+)\]\]/,
+    );
+
+    if (!dumpPathMatch) {
+      throw new Error("No dump path found in messages list");
+    }
+
+    const dumpFilePath = dumpPathMatch[1];
+    const dumpContent = fs.readFileSync(dumpFilePath, "utf-8");
+    const parsedDump = JSON.parse(dumpContent);
+
+    // Get the last message from the dump
+    const messages = parsedDump.body.messages;
+    const lastMessage = messages[messages.length - 1];
+
+    expect(lastMessage).toBeTruthy();
+    expect(lastMessage.content).toBeTruthy();
+
+    // The content is an array with text and image parts
+    expect(Array.isArray(lastMessage.content)).toBe(true);
+
+    // Find the text part and verify it mentions the PNG attachment
+    const textPart = lastMessage.content.find(
+      (part: any) => part.type === "text",
+    );
+    expect(textPart).toBeTruthy();
+    expect(textPart.text).toMatch(/annotated-screenshot-.*\.png/);
+    expect(textPart.text).toMatch(/image\/png/);
+
+    // Find the image part and verify it has the correct structure
+    const imagePart = lastMessage.content.find(
+      (part: any) => part.type === "image_url",
+    );
+    expect(imagePart).toBeTruthy();
+    expect(imagePart.image_url).toBeTruthy();
+    expect(imagePart.image_url.url).toMatch(/^data:image\/png;base64,/);
+  },
+);